In EP 1 887 200 A1 and in DE 60 2004 000 705 T2 are described valve flap devices with a tubular cast iron housing having valve flaps mounted by a shaft to control the flow through them.
The throttle devices described in EP 835 998 A1 and in DE 20 2008 005 992 U1 have tubular cast iron throttle housings that have been machined to produce the final geometry.
In DE 100 42 923 A1 is described a throttle mechanism in which the shaft for the valve flap is mounted on both sides and the bearing is press-fitted into the valve housing.